Heartfire is the latest installment in the Alvin Maker series by Orson Scott Card. Alvin's wife Peggy, a torch (able to see people's futures through their heartfires) is in Camelot, capital of the Crown Colonies. She has forseen a terrible war over slavery, and seeks to move people's choices away from that by contacting the people who oppose slavery.

However, she discovers that these people are merely creating an appearance, and have no real intention of ameleorating the institution. Worse, some terrible magic is stealing away the spirit of the slaves, and Alvin's troublesome brother Calvin is poking around. When Peggy humiliates Calvin, he decides to prove himself by finding out just who is stealing the slaves' souls. In doing so, he falls into the power of the soul-stealer.

Meanwhile, Alvin struggles to understand how he is supposed to build that Crystal City he saw so many years ago in Tenska-tawa's vision atop the waterspout. He doesn't even know his own skills, and despairs of finding anyone to teach him. After young Arthur objects to the shooting of birds just to paint pictures and instead uses his knack of communications with birds to get them to pose, Audobon joins his company.

In time he decides to cross over to New England, although this puts them at risk of the Puritan witch-hunters. An accidental encounter with the daughter of parents hanged as witches leads to an accusation, and Alvin's friend Verily decides to not only free Alvin, but overturn the witchcraft laws as well.

Alvin must not only win his case, but must find some way to save his brother Calvin as well, and get everyone safely back to the freedom of the United States (which in that time takes in only the Middle Atlantic states and part of the Midwest).